The present invention relates to key panels in general and more specifically to a key panel formed from a single strip of switch material and a method for making the key panel.
Key panels or keyboards have been used for decades to provide input and control instructions to electronic devices and systems. Early key panel systems were discrete systems, typically comprising an array of individual mechanical switches arranged and mounted so as to form the desired key panel configuration. For example, early QWERTY (e.g., typewriter-style) key panel systems were constructed according to this architecture. However, besides being cumbersome, heavy, and prone to malfunction due to foreign object contamination, such discrete type key panel or keyboard systems are expensive and difficult to produce.
Partly in an effort to solve some of the problems associated with discrete component key panel systems, key panel systems have been developed in which the various switches are provided on thin, flexible substrates or membranes. Such key panel systems are often generically referred to as membrane type key panel systems. While many different types of membrane type key panel systems exist and are being used, a typical membrane type key panel system comprises a laminated or layered structure in which a bottom membrane layer or sheet is provided with a plurality of switch elements that correspond to each desired input key. An overlying flexible layer or membrane may be provided with one or more raised portions or xe2x80x9cdomesxe2x80x9d thereon that are aligned with the switch contacts provided on the bottom layer or membrane. Each switch on the bottom membrane may be actuated by depressing the corresponding dome on the overlying or top layer. Membrane type key panels of the type just described have become very popular and are widely used in modern electronic devices and systems due to their reliable operation, light weight, and rugged construction.
One problem that remains with such membrane type key panel systems is that they are not readily adaptable to varying panel or keyboard configurations. As an example, a currently available membrane type key system is produced as a two dimensional sheet or panel having a size and shape that corresponds to the specific key panel layout for the particular device in which the key panel is to be used. Therefore, if the key panel layout is changed, an entirely new sheet or panel of the switch membrane material must be produced that corresponds to the changed key panel layout. Moreover, if a user desires to utilize a key panel configuration wherein the keys are placed around the periphery of the panel, such as for example, if the keys are to be placed around a centrally located two dimensional display device (e.g., a CRT or and LCD display), the sheet material located in the corresponding central region of the key panel will need to be removed, thus wasted, in order to accommodate the display device. Such waste increases the overall cost of the key panel device. Another disadvantage associated with currently available membrane type key panel systems is that two dimensional sheets or panels are difficult to ship and store, particularly if the key panel in which they are to be used is relatively large.
A key panel according to one preferred embodiment of the invention comprises a key pad having a number of key sites provided thereon that define an aspect ratio for the key pad. A strip of printed wiring material is positioned adjacent the key pad. A number of switch contact sites provided on the strip of printed wiring material define an aspect ratio for the strip of printed wiring material that is greater than the aspect ratio of the key pad. The strip of printed wiring material is provided with at least one fold therein so that each of the number of switch contact sites provided on the strip of printed wiring material is generally aligned with a corresponding one of the number of key sites provided on the key pad.
Also disclosed is a method for fabricating a key panel that comprises the steps of: Selecting a key pad having a number of key sites provided thereon which define an aspect ratio for the key pad; selecting a strip of printed wiring material having a number of switch contact sites thereon that define an aspect ratio that is greater than the aspect ratio of the key pad; and folding the strip of printed wiring material so as to align ones of the number of switch contact sites with corresponding ones of the number of key sites.